Setter but not for Style in WPF? - wpf

Question

I know how Triggers with Setters work in WPF, and I know that Setters can only change Style properties. Is there something equivalent to the Setter for non-Style properties? I really want to be able to change a property on custom object that is instantiated in XAML. Any ideas?
Edit: While Setters can update any dependency property, I am attempting to do this within an EventTrigger, which I forgot to specify. There is this workaround, but I'm not sure if it is really best practice. It uses storyboards and ObjectAnimationUsingKeyFrames. Is there anything wrong with this?

Answer 1

Using Interactivity from the Blend SDK you can do this in XAML, you only need to create a TriggerAction which sets the property.
Edit: There already is such an action in another namespace: ChangePropertyAction
In XAML you can use this namespace: http://schemas.microsoft.com/expression/2010/interactions
Tested example:
public class PropertySetterAction : TriggerAction<Button>
{
public object Target { get; set; }
public string Property { get; set; }
public object Value { get; set; }
protected override void Invoke(object parameter)
{
Type type = Target.GetType();
var propertyInfo = type.GetProperty(Property);
propertyInfo.SetValue(Target, Value, null);
}
}
<StackPanel>
<StackPanel.Resources>
<obj:Employee x:Key="myEmp" Name="Steve" Occupation="Programmer"/>
</StackPanel.Resources>
<TextBlock>
<Run Text="{Binding Source={StaticResource myEmp}, Path=Name}"/>
<Run Name="RunChan" Text=" - "/>
<Run Text="{Binding Source={StaticResource myEmp}, Path=Occupation}"/>
</TextBlock>
<Button Content="Demote">
<i:Interaction.Triggers>
<i:EventTrigger EventName="Click">
<t:PropertySetterAction Target="{StaticResource myEmp}"
Property="Occupation"
Value="Coffee Getter"/>
</i:EventTrigger>
</i:Interaction.Triggers>
</Button>
</StackPanel>
Note that with Value being an object default ValueConversion will not take place, if you enter a value as an attribute (Value="Something") it will be interpreted as a string. To set an int for example you can do this:
xmlns:sys="clr-namespace:System;assembly=mscorlib"
<t:PropertySetterAction Target="{StaticResource myEmp}"
Property="Id">
<t:PropertySetterAction.Value>
<sys:Int32>42</sys:Int32>
</t:PropertySetterAction.Value>
</t:PropertySetterAction>

Answer 2

Have you declared the properties that you want to set as dependency properties? I can't find the project I did this in, but I am pretty sure that is what fixed it for me.
I tried implementing something pretty simple, and got the following:
The property "Type" is not a DependancyProperty. To be used in markup, non-attached properties must be exposed on the target type with and accessible instance property "Type". For attached properties the declaring type must provide static "GetType" and "SetType" methods.
Here is a dependancy property registration example from another project of mine:
Public Shared TitleProperty As DependencyProperty = DependencyProperty.Register("Title", GetType(String), GetType(SnazzyShippingNavigationButton))
In the above example, SnazzyShippingNavigationButton is the Class Name of which the property is a member.
And the associated property declaration:
<Description("Title to display"), _
Category("Custom")> _
Public Property Title() As String
Get
Return CType(GetValue(TitleProperty), String)
End Get
Set(ByVal value As String)
SetValue(TitleProperty, value)
End Set
End Property
Description and Category attributes only really apply to the IDE designer property grid display.